1. Field of the Invention
This invention relates to a self-unloading bulk material truck and/or trailer beds having a discharge conveyor. More specifically, the invention relates to an improved chain bar for connecting the chains, and carrying the belt sections, of the discharge conveyor.
2. Related Art
Discharge conveyors have been developed to provide a self-unloading feature for bulk material beds, such as those provided on trailers or trucks for transport of potatoes, sugar beets, or garbage, for example. Bulk beds and conveyors of this general type are described in Eisenman U.S. Pat. No. 4,055,265 (issued Oct. 25, 1977), Eisenman U.S. Pat. No. 4,230,360 (issued Oct. 28, 1980), Gust U.S. Pat. No. 4,664,583 (issued May 12, 1987), Whitehead U.S. Pat. No. 4,741,431 (issued May 3, 1988), and Gust U.S. Pat. No. 5,102,285 (issued Apr. 7, 1992).
An example of a recent Eisenman self-unloading bed design, such as is available from Trinity Trailer, 8200 Eisenman Road, Boise, Id., 83716, is shown in FIGS. 1 and 2. This bed and its discharge conveyor have many similarities to those drawn in Eisenman U.S. Pat. Nos. 4,230,360, and 4,055,265. Referring to call-out numbers included in the present inventors' attached FIGS. 1 and 2, the trailer 10 is typically connected to a tractor (not shown) at the trailer front end 12. The bed front wall 14, upright rear wall 16, left and right side walls 18, 18′ form a substantial portion of the bed, with the bottom floor being formed by an endless conveyor 20 system. The lower portions 22, 22′ of side walls 18, 18′ slant toward the middle, so that the bulk material tends to fall/slide down toward the conveyor 20. This way, as the endless conveyor moves along the bottom of the bed to carry material out of the opening 24 in the rear wall, the bulk material falls down to continuously “refill” the conveyor until the bed is empty.
A conveyor preferred by the inventors includes a chain system comprising two spaced-apart endless chains 26, 26′ each in a loop that extends horizontally substantially all the length of the bed. See, for example, U.S. Pat. No. 4,055,265, which is incorporated herein by this reference. Chain bars 30 extend between the chains, at spaced intervals along, and perpendicular to, the lengths of the chains 26, 26′ to connect the chains together and to provide an anchoring place for the belt flaps 40 of the conveyor. Driven by sprockets (see, for example, FIG. 5 of U.S. Pat. No. 4,055,265), the chains 26, 26′ carry the chain bars 30 along a floor liner 32, which is generally horizontal, flat and smooth, Ultra High Molecular Weight (UHMW) polymer sheet. The belt portions 40 ride along with the chain bars 30, in effect, dragged along the UHMW floor liner carrying the bulk material in the bed. The belt portions 40 in the working (top) flight lie generally horizontally and overlap, to create a substantially continuous belt moving from the front to the rear of the bed. As the belt flaps 40 reach the opening 24 in the rear wall 16, they continue to be pulled by the chains, that is, down and underneath the floor liner 32 to travel in the opposite direction (toward the front of the bed). In doing so, the bulk material on each belt flap 40 is dumped out of the bed. As each flap 40 “turns the corner” to begin traveling underneath the floor liner, it may flip outward and downward, to at least temporarily leave contact with the adjacent (following) flap. Depending upon the design of the bottom side of the floor system and the undercarriage of the trailer, the belt flaps may then regain their overlapping contact with each other for part of the journey underneath the trailer. For example, as shown in FIG. 3B, the belt flaps 40 traveling underneath the floor liner and toward the front end stay close to each other and generally horizontal for several feet over the rear wheels. Then, when there is room (in this example, in front of the rear wheels) for the belt flaps 40′ to fall down away from each other, the flaps 40′ fall down away from each to hang down in a substantially vertical position. This way, the belt flaps 40, 40′ tend to be self-cleaning. Once each belt flap 40′ travels again to the front of the bed, it is pulled up again to the top, working flight, so that it again lies generally horizontally and overlapping the next (following) flap to carry bulk material toward the rear of the bed.
Conventional chain bars 30 are generally U-shaped, with a main body 50, and two legs 52, 52′ depending from the body 50. Such conventional chain bars 30 may be seen in FIG. 5 of U.S. Pat. No. 4,055,265, called-out as number 35, and in FIG. 5 of this document.
Alternative chain bars are shown in Gust U.S. Pat. No. 4,664,583 (FIG. 4, call-out 37; see column 3, lines 38-44 and column 4, lines 39-45) and in Gust U.S. Pat. No. 5,102,285 (FIG. 4, call-out 37; see column 3, lines 38-44). The Gust chain bars have three portions and are generally Z-shaped in cross-section.
Still, there is a need for an improved conveyor system with improved chain bars, and the invention meets this need.